Drop away fire vent

ABSTRACT

A fire vent having a closure panel or partition which normally closes a tubular vent chamber or passage defined by an annular frame, with a support means for normally holding the closure in place, even against direct loading, but which collapses in response to the presence of heat, as from a fire, to drop the closure out of the way and open up the tubular chamber and thus provide a vent.

United States Patent [191 Veen, Jr. Jan. 29, 1974 [5 DROP AWAY FIRE VENT 1,613,023 1/1927 Diete 292/23 1751 Inventor: James veer-1J6, Grand Rapids, 533323333 3/1322 $213311: 1:13. 22? Mlch- 3,473,276 10/1969 Back 52/200 [73] Assignee: Hillsdale Industries, Inc., Grand FOREIGN PATENTS OR APPLICATIONS Raplds 594,559 3/1960 Canada 49 7 [22] Filed; J 1972 6,716,335 5/1968 Netherlands 52/200 [21] Appl' 260436 Primary Examinerl-1enry C. Sutherland 4595521 gji'lqjifi s a [52] U.S. C1 52/1, 49/7, 49/8, t y, g t, or F 1 H n v d, H iz nga 52/200, 292/1 1 & Cooper [51] Int. Cl E05f 15/20 57 A T [58] Field of Search 52/1 232; 49/5 8; A fire vent having a closure panel or partition which normally closes a tubular vent chamber or passage de- [56] References Cited fined by an annular frame, with a support means for normally holdmg the closure in place, even against d1- UNITED STATES PATENTS rect loading, but which collapses in response to the 2,803,318 8/1957 Nickerson 52/232 presence of heat, as from a fire, to drop the closure Levy out of the way and open up the tubular chamber and 197,1 [5 11/1877 Frees 292/50 thus provide a vent 1,078,361 11/1913 Lawrence r 49/7 1,559,261 10/1925 Konsalik 52/1 17 Claims, 4 Drawing Figures PATENTEDJAN 29 I974 SHEET 1 BF 2 l4 M r H63 FIGJ DROP AWAY FIRE VENT BACKGROUND OF THE INVENTION in response to heat, as by use of temperature-sensitive solder connections or joints, or by fusible links, and some vents have been both manually and automatically actuable. Typically, most such vents have used doors which open by swinging upon any of a variety of hinge mounts or the like, often with a spring-loading leverage arm. mechanism triggered by a fusible link which normally holds the doors closed.

In many cases, it is desirable to have the vent provide a light-admitting skylight function as well as an airadmitting or heat-releasing venting function, as by use of a translucent or even transparent closure panel, for example, an acrylic or other plastic dome. Such a closure does not, however, readily lend itself to known types of automatic releasing and opening structures and, in addition, there is a need for improvement in such releasing structures, particularly in making the same less expensive and simpler in construction, while at the same time improving reliability of operation. It is desirable, for example, to have the least possible number of mechanical elements within the vent tube or chamber, especially since such structures are often damaged by a fire to the extent that they cannot be reused, or at least to the extent that they require reworking for subsequent use. At the same time, however, in its normally closed position, the closure panel must reliably and securely close the vent, even against direct loading such as occurs when a workman or other person walks directly over the vent, applying full weight to the latter; indeed, such structural reliability and strength is normally a fixed requirement of building and insurance codes, just as reliable venting operation is usually a rigid requirement of most building and fire codes.

SUMMARY OF THE INVENTION The present invention provides a new concept in automatic self-releasing mounting means for a fire vent of the general nature referred to above, and a major objective of the invention is to provide a simple mounting structure for such a light-admitting closure panel which merely collapses away from under the panel in the presence of elevated temperatures from a fire or the like and allows the closure panel to drop directly out of the opening it normally closes, to provide a complete fire vent.

At the same time, it is a major objective of the invention to provide an automatically-collapsing support structure for a closure panel of the above character, which will normally reliably close the vent, even against direct loading, such as may be provided for example by the weight of a person standing directly on the closure.

In accordance with the invention, a drop-away fire vent is provided which includes a curbing or frame means defining at least in part the passage to be vented, with a portion at least partially hooding such passage to provide a bearing surface against which the closure panel seats, from beneath. The closure panel has an outer periphery of generally the same size and shape as the passage to be vented, but is somewhat smaller, so that the closure can drop through the passage. A first support element, or series thereof, is movably carried on the curbing or frame means, and is held in a supporting position by an elongated tension member having a heat-responsive fusible link or the like which releases in the presence of heat. A second support element or supportmeans is disposed in compressive engagement between the first such element or series thereof and the closure panel, such that when the tension member is released by separation of the fusible link in the presence of heat, the first support element is no longer held in position but is instead unbalanced with respect to gravitational forces and also with respect to the weight of the closure panel. The first and the second support elements thus drop away, allowing the closure panel to drop out of position and fully open the vent passage.

The foregoing major objectives and advantages of the invention, together with other objectives and advantages equally a part of the invention, will become more apparent from a consideration of the following detailed specification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side elevation showing a first form of device in accordance with the invention;

FIG. 2 is an overhead plan view of the apparatus shown in FIG. 1;

FIG. 3 is an enlarged, fragmentary side elevation of part of the structure shown in FIG. 1; and

FIG. 4 is an enlarged, fragmentary side elevational view similar to FIG. 3 but showing a somewhat modified apparatus in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated generally in FIGS. 1 and 2, and also with reference to the emboidment of FIG. 3, the dropaway fire vent 10 of the invention includes, generally, a frame means 12, typically of substantially rigid metal construction, which surrounds the vent opening and which has an upstanding wall portion 14 (FIGS. 1 and 3), a right-angled outwardly-projecting base 16 for mounting the frame upon a roof orwall, and a downwardly-opening channel-shaped upper portion 18, atop which is positioned a complementary-shaped cap 20 having and upstanding skirt or flange projection 22 (FIG. 3), atop which mounts a flange portion 24 that partially hoods the open central passage 26 surrounded or defined by the upstanding wall portions 14. That is, flange portions 24 extend laterally inwardly of the passage with respect to wall portions 14, and both ring the opening 26.

A canopy-like closure panel or partition 28, which may be in the form of a translucent plastic dome, closes the open central passage 26. The outer periphery of the dome or closure panel has substantially the same size and shape as that of the passage 26 (which may be rectangular, or of circular or other curving periphery), but is at least slightly smaller than the passage in outer or diametral dimension, so as to be movable axially therewithin. As illustrated, the peripheral edges of the dome or panel 28 rest immediately beneath, and in contact with, the inwardly-directed edges of flange portion 24.

The dome 28 is held in the position just stated by a collapsible mechanism, one form of which is illustrated in detail in FIG. 3. Referring to such figure, it will first be seen that the cap 20 seats directly atop the similarlyshaped, but somewhat smaller, channel portion 18 of the frame means, and that the flange portion 24 may be mounted atop the upstanding skirt projection 22 of the cap 20 as, for example, by a series of machine screws 30 or the like. The cap 20 has a downwardly-depending interior leg 32 which seats flush against the inside of upright wall 14 and, at the uppermost extremity of interior leg 32, the cap 20 defines an upwardly-projecting ridge 34 of generally rounded configuration. Seated directly atop ridge 34 is a first support element 36, having a groove in its lower extremity which is shaped complementary to, and which receives, the ridge 34. Also, support element 36 has a downwardly-depending leg projection 38 which fits flush against the interior leg 32 of the cap 20 for bracing support thereagainst. In addition, support element 36 has an outwardly-directed leg or flange portion 40 which bears against the interior face of an inwardly-angled portion of upstanding projection 22, which is rigid in structure and rigidly positioned.

The primary portion of first support element 36 comprises a web 42 which extends angularly inwardly of the other portions mentioned above, into the central passage 26, and the uppermost edge of the primary web portion 42 supports a second support element 44 which, in its overall nature, comprises a continuous frame of an annular nature (rectangular in the embodiment illustrated), having an open central area and a closed perimeter whose shape is substantially that of the tubular passage 26 and of the outer perimeter of the dome 28. Support element 44 has an upstanding leg portion 46, atop which seats a somewhat resilient mounting pad 48 of plastic or rubbery syntheticmaterial having a downwardly-opening slot into which the upstanding leg 46 is received to hold the mounting pad in place. Mounting pad 48 has a generally flat upper surface upon which rests the lower peripheral surface of the dome or closure panel 28, whereby the latter is held in place against flange 24, thereby holding the panel or dome 28 in the position referred to previously. It should be noted that the peripheral edges of panel 28 are preferably not clamped rigidly or with extreme force by the aforementioned structure, since it is better to allow these edges to move between pad 48 and flange 24 as the dome or panel 28 contracts and expands with temperature variations.

As illustrated, the central section of support 44 is angled at least slightly upwardly and inwardly, and the innermost edge of this support defines an upwardly curved curbing 50. Support 44, in addition to its supportive functions already described, thus provides a condensationcollecting apron means which extends completely around the underside of the periphery of the dome or closure 28, to collect the moisture which inevitably condenses or collects on the underside of the dome, and to direct such moisture outwardly, for example, through a series of appropriate openings or passages 47 extending laterally through the upright leg 46. The moisture-collecting capabilities of the second support 44 are further facilitated by a flexibly yieldable apron portion 52, which may be a strip of readily flexible but basically self-supporting plastic such as vinyl, and which is held in place between a pair of spaced flange extremities 54 of support 44 that are crimped together upon the flexible apron portion to mount the same. As illustrated, the flexible apron portion 52 extends outwardly, over parts of the frame means 12, i.e., over the upright wall 14 and the upstanding projection 22, whose uppermost portions immediately above the mounting screws 30 may define a condensate channel 56, which is relieved through downwardly-extending openings therethrough (not specifically illustrated) between the spaced mounting screws 30. In this manner, condensation from the underside of the closure dome 28 runs laterally outwardly and downwardly thereon, drips or runs downwardly onto the second support element 44, runs outwardly thereon over the flexible apron portion 52, and ultimately leaves the vent chamher by falling onto the top of cap and running downwardly and outwardly over the channel portion 18.

The central web portion 42 of the first support 36 mounts a leverage arm and overbalance weight member 58, (FIG. 3), as by a threaded end on the latter member passing through an appropriate aperture in the web 42 and secured in place by a nut disposed on either side of the web and tightened in place. As stated above, the support element 36 rests atop the interior ridge 34 of cap 20, with the uppermost extremity of support 36 serving to brace against and support the upper support element 44, which in turn holds the canopy or dome 28 in place. This support arrangement is not, however, stable or free-standing absent further retention means, since it may be readily observed that without some further support or retention means, the leverage arm 58 and the remainder of support element 36 constitutes a considerably overbalanced structure which will fall by gravity if not otherwise retained, particularly under the weight of the second support 44 and the canopy 28. The additional support is provided by a tension member 60 which may take the form of a cable having a series-mounted coil spring 62 (FIG. 2), as well as a seriesmounted fusible link 64 or like heat-responsive separation means. As illustrated, the cable or tension means 60 extends around the downwardly-curving innermost end extremity 58a of the arm 58 (FIG. 3).

As stated previously, the upper support 44 is a continuous rectangular (or other annular shape) frame having a shape corresponding substantially to that of the perimeter of the dome 28; however, as will be seen from FIGS. 1 and 2, there are a plurality of individual lower supports 36, each having a length which is less than the total length of a side of the frame means or of the dome, and each lower support 36 resting atop the ridge 34 about the periphery of the central passage 26. Also, each of the lower supports 36 has a leverage arm 58, and all of the latter are joined together by the tension member 60, which thus fonns a closed loop which includes the aforementioned coil spring 62 for maintaining the loop under tension, and the seriesconnected fusible link 64. When so interconnected, and with inwardly-directed force applied to the ends of the arms 58, the lower supports 36 are securely retained in position, wherein they readily support the upper support frame 44 and the canopy 28. In addition, this supportive arrangement will also readily withstand reasonable vertical loading from above, including for example the weight of a person walking directly over ends of the arms 58. Immediately, the arms 58, with the other overbalancing weight and forces acting upon the different lower supports 36, pivot each of the latter to the position in phantom in FIG. 3, from which position the lower supports 36 are all free to fall by gravity (although they may, of course, be mounted by flexible wire, chain, or the like, so that they do not fall entirely through the passage 26 and into the building). Upon such movement of the lower supports 36, the upper support frame 44 is totally unsupported, as is the canopy 28. Consequently, both of these units fall directly downwardly by gravity, to promptly open the central chamber 26 and provide the desired vent. In this connection, the flexibility yieldable apron portion 52 secured to the support frame 44 readily yields, folding upwardly to pass over the top of the upstanding wall projection 22, as well as over any further lateral obstructions in the passage, thereby allowing the entire support 44 to drop downward without hesitation. As

mentioned above in connection with the lower support elements 36, the upper support frame 44, and if desired the canopy 28 itself, also may all be suspended by flexible wires or chains from some desired part of the frame means 14 or the like, to arrest their downward fall at some desired position which nonetheless leaves the central chamber 26 freely open as a vent.

An alternative embodiment for the structure illustrated in FIG. 3 and described above is illustrated in FIG. 4, wherein generally corresponding elements carry the same numerical designation as in FIG. 3, but preceeded by the prefix number 1.

Referring to FIG. 4,,it may be seen that the frame means 112 once again has a foot or base 116 for mounting purposes and an upstanding wall 114. Also, a channel member 118 is provided at the top of upstanding wall 114, but in'this case the channel comprises an integral part of a compound extrusion 70 which is secured in place atop the upstanding wall 114, as by a series of spaced screws 72. The compound extrusion 70 has an upstanding projection 122 as an integral part thereof, such projection being analogous to the projection 22 of FIG. 3. Atop projection 122 is a flange portion 124, secured in place by machine screws 130 or the like. As in the case of the FIG. 3 apparatus, the peripheral edges of the dome or closure 128 are disposed immediately beneath the inturned flange 124; in this case, however, the support means is somewhat different.

More particularly, the compound extrusion 70 defines an elongated pivot ridge 74, of rounded cross section, upon which is suspended a first support element 236 having a J-shaped curved end extremity 237, having a shape complementary to that of the pivot ridge 74. As illustrated, in its supporting position element 236 extends generally horizontally or perpendicular to the upstanding wall 114 of the frame means, and a lever arm 158 which is secured to, or an integral part of, the member 236 projects directly inwardly thereof, terminating in a downwardly curved end 158a which receives a tension means or cable 160, as before.

Support element 136 rests atop support 236, but is a separate piece from the latter, of substantially the same length. Support element 236 defines a seat for the lower edge of support 136, such seat comprising a longitudinal groove of rounded cross section in the upper surface of support 236, approximately above, but somewhat inwardly of, the rounded pivot ridge 74; also,

support 236 includes an integral, upstanding lip projection 76 which nests flatly against the adjacent rear surface of support 136 when the latter is in place. Similarly, the continuous annular upper support member 144 defines a seat for the top edge of each of the individual supports or braces 136, each such seat comprising a rounded longitudinal groove disposed between integral downwardly-depending projections 78 and 80 which also extend longitudinally of support 144 and which flank opposite sides of members 136, at the top of the latter. As may be seen, the projection 80 also cooperates with a flange extremity 158 to hold the upper margin of a flexible apron 152 and retain the latter in place, such that condensate from the underside of dome 128 may be collected in the same basic manner as described above and will run off over apron 152 and outwardly through apertures 153 in upstanding projection 122. As illustrated, the outer edge of apron 152 may be supported by flange portions 154 forming a part of projection 122 and disposed directly beneath the apertures 153. Of course, the flexible apron 152 will readily bend to pass over the flange portions 154, as well as other structures disposed below the latter, at such time as support means 144 may drop downwardly.

The structural arrangement just described for the embodiment of FIG. 4 retains the dome or closure 128 in position in a manner very similar to the structure shown in FIG. 3. With the parts in their relative positions illustrated, the dome or closure 128 is securely held in position even against downward vertical loading. That is, even under vertical loading the canopy cannot be moved downwardly so long as the tension member is intact. The structural integrity of the mount can readily be appreciated when the continuous perimetral nature of the upper support 144 is considered, since no single part or segment of this support can move laterally, being restrained by the other parts of this member. Consequently, downward force upon support 144 merely places a vertical compressive and bending load upon the medial support 136, and the top of the latter is in effect held by a force couple between projections 78 and 80, while the lower end is restrained from outward movement by the lip 76 of lower support 236 and, in turn, by the cable or tension member 160.

When the tension member 160 is released by separation of its fusible link component, each of the supports 236 is clearly in a completely overbalanced condition with respect to gravitational forces, both as a result of its own configuration and as a result of the weight applied to it by the other parts of the support means and by the canopy itself. As a result, any separation of the tension means 160 immediately results in a downward pivoting of the lower supports 236 about the rounded pivot ridge 74, during which movement of the supports 236 kick out or free the lower extremity of the different medial supports 136, whereupon the latter members drop downwardly, immediately followed by the upper support 144 and the dome 128, opening the vent.

It is entirely conceivable that upon examining the foregoing disclosure, those skilled in the art may devise embodiments of the concept involved which differ somewhat from the embodiment shown and described herein, or may make various changes in structural details to the present embodiment. Consequently, all such changed embodiments or variations in structure which utilize the concepts of the invention and clearly incorporate the spirit thereof are to be considered as within the scope of the claims appended herebelow, unless these claims by their language specifically state otherwise.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

l. A drop-away fire vent, comprising in combination: means defining the periphery of an opening and including a fixed generally rigid frame portion and a plurality of support elements carried on fulcrum points on said frame portion at spaced locations around said periphery for movement between a first load-supporting position and a second non-supporting position, said elements including arm portions projecting inwardly of said opening when said elements are in said first position; a canopy means, including a closure member having a smaller periphery than that of said opening, a vertically anchored stop structure above said closure member and contacted by the latter from beneath, and means for supporting said closure member in place against said stop structure and upon said support elements when the same are in their said first position; said closure member being movable through said opening upon movement of said support elements to their second said position, to uncover said opening; means for collecting condensation from the underside of said canopy closure member and directing such condensation away from the perimeter of such member; and means for interconnecting said inwardly-projecting arm portions of said support elements when the latter are in said first position thereof, and for holding said elements in position maintaining said canopy closure member in contact with said stop structure, said means including a releasable portion having heat-responsive means for releasing said support elements in the presence of heat for movement to said second position, whereby said canopy closure member moves through said opening and uncovers it.

2. The apparatus as defined in claim 1, wherein said support elements comprise at least one balance weight portion having sufficient mass to move such portions under gravitational force when said interconnecting means is released in the presence of heat.

3. The apparatus as defined in claim 2, wherein said fulcrum points comprise structure on said frame portion for rockably mounting said support elements, such that said movement of such element is at least in part a rocking movement.

4. The apparatus as defined in claim 1, wherein said fulcrum points comprise a free open pivot mount for said support elements such that in said second position of said elements the same are unsupported and free to move by gravity.

5. The apparatus as defined in claim 1, wherein said means for interconnecting said support elements includes an elongate tension member, and wherein said heat-responsive means includes a heat-releasing coupling connected along the length of such tension member.

6. The apparatus as defined in claim 5, wherein said plurality of support elements have lever arm portions extending generally toward the inside of said opening, and wherein said tension member comprises a loop interconnecting said lever arm portions.

7. The apparatus as defined in claim 6, wherein said lever arm portions further comprise balance weight portions having sufficient mass to move the respective support elements to their said second position when said tension member is released by said coupling.

8. The apparatus as defined in claim 1, wherein said means for collecting condensation comprises at least one apron member extending beneath the perimeter of said canopy closure member and outwardly thereof over portions of said frame means.

9. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend over portions of said frame means.

10. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend under at least 5 portions of the perimeter of said canopy closure member.

11. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend into contact with said means for supporting said canopy closure member in place and are supported thereby.

12. A drop-away fire vent, comprising in combination: frame means defining a generally tubular upright chamber and including fixed, generally rigid wall portions and flange portions above said wall portions which partially hood said tubular chamber; a closure means having an outer periphery generally corresponding to, but at least somewhat smaller than, the cross section of said chamber, said closure means disposed within said chamber beneath said flange portions; and collapsible support means between said rigid wall portions and said closure means, for normally supporting the latter in position beneath said flange portions but for collapsing in response to heat to allow said closure means to drop downwardly by gravity within said chamber to vent the latter, said collapsible support means comprising a plurality of mutually spaced movably mounted individual supports in load-bearing engagement between said rigid wall portions and said closure means and heat-responsive means for releasing said supports from such engagement to thereby remove the support of said closure means, at least certain of said movably mounted supports including a first support element movably carried on said rigid wall portions and a separate second support element in compressive wedging engagement between the first support element and said closure means.

13. The apparatus as defined in claim 12, wherein said closure means includes a closure partition whose edges define said outer periphery and a mounting frame for said partition, said mounting frame having at least two oppositelydisposed rail portions underlying and supportively engaging a pair of oppositely-disposed partition edges.

14. The apparatus as defined in claim 13, wherein said rail portions urge the said partition edges which they engage upwardly against said flange portions hooding said tubular chamber.

15. A drop-away fire vent, comprising in combination: frame means defining a generally tubular upright chamber and including fixed, generally rigid wall portions and flange portions above said wall portions which partially hood said tubular chamber; a closure means having an outer periphery generally corresponding to, but at least somewhat smaller than, the cross section of said chamber, said closure means disposed within said chamber beneath said flange portions; and

collapsible support means between said rigid wall portions and said closure means, for normally supporting the latter in position beneath said flange portions but for collapsing in response to heat to allow said closure means to drop downwardly by gravity within said chamber to vent the latter; said closure means including a closure partition whose edges define said outer periphery and a mounting frame for said partition, said mounting frame having at least two oppositely-disposed rail portions underlying and supportively engaging a pair of oppositely-disposed partition edges, said rail portions including a condensation-collecting apron means disposed beneath and extending both laterally inwardly and outwardly of certain of said partition said frame means. 

1. A drop-away fire vent, comprising in combination: means defining the periphery of an opening and including a fixed generally rigid frame portion and a plurality of support elements carried on fulcrum points on said frame portion at spaced locations around said periphery for movement between a first load-supporting position and a second non-supporting position, said elements including arm portions projecting inwardly of said opening when said elements are in said first position; a canopy means, including a closure member having a smaller periphery than that of said opening, a vertically anchored stop structure above said closure member and contacted by the latter from beneath, and means for supporting said closure member in place against said stop structure and upon said support elements when the same are in their said first position; said closure member being movable through said opening upon movement of said support elements to their second said position, to uncover said opening; means for collecting condensation from the underside of said canopy closure member and directing such condensation away from the perimeter of such member; and means for interconnecting said inwardlyprojecting arm portions of said support elements when the latter are in said first position thereof, and for holding said elements in position maintaining said canopy closure member in contact with said stop structure, said means including a releasable portion having heat-responsive means for releasing said support elements in the presence of heat for movement to said second position, whereby said canopy closure member moves through said opening and uncovers it.
 2. The apparatus as defined in claim 1, wherein said support elements comprise at least one balance weight portion having sufficient mass to move such portions unDer gravitational force when said interconnecting means is released in the presence of heat.
 3. The apparatus as defined in claim 2, wherein said fulcrum points comprise structure on said frame portion for rockably mounting said support elements, such that said movement of such element is at least in part a rocking movement.
 4. The apparatus as defined in claim 1, wherein said fulcrum points comprise a free open pivot mount for said support elements such that in said second position of said elements the same are unsupported and free to move by gravity.
 5. The apparatus as defined in claim 1, wherein said means for interconnecting said support elements includes an elongate tension member, and wherein said heat-responsive means includes a heat-releasing coupling connected along the length of such tension member.
 6. The apparatus as defined in claim 5, wherein said plurality of support elements have lever arm portions extending generally toward the inside of said opening, and wherein said tension member comprises a loop interconnecting said lever arm portions.
 7. The apparatus as defined in claim 6, wherein said lever arm portions further comprise balance weight portions having sufficient mass to move the respective support elements to their said second position when said tension member is released by said coupling.
 8. The apparatus as defined in claim 1, wherein said means for collecting condensation comprises at least one apron member extending beneath the perimeter of said canopy closure member and outwardly thereof over portions of said frame means.
 9. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend over portions of said frame means.
 10. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend under at least portions of the perimeter of said canopy closure member.
 11. The apparatus as defined in claim 8, wherein said apron member includes a flexibly deformable portion and at least portions of said apron extend into contact with said means for supporting said canopy closure member in place and are supported thereby.
 12. A drop-away fire vent, comprising in combination: frame means defining a generally tubular upright chamber and including fixed, generally rigid wall portions and flange portions above said wall portions which partially hood said tubular chamber; a closure means having an outer periphery generally corresponding to, but at least somewhat smaller than, the cross section of said chamber, said closure means disposed within said chamber beneath said flange portions; and collapsible support means between said rigid wall portions and said closure means, for normally supporting the latter in position beneath said flange portions but for collapsing in response to heat to allow said closure means to drop downwardly by gravity within said chamber to vent the latter, said collapsible support means comprising a plurality of mutually spaced movably mounted individual supports in load-bearing engagement between said rigid wall portions and said closure means and heat-responsive means for releasing said supports from such engagement to thereby remove the support of said closure means, at least certain of said movably mounted supports including a first support element movably carried on said rigid wall portions and a separate second support element in compressive wedging engagement between the first support element and said closure means.
 13. The apparatus as defined in claim 12, wherein said closure means includes a closure partition whose edges define said outer periphery and a mounting frame for said partition, said mounting frame having at least two oppositely-disposed rail portions underlying and supportively engaging a pair of oppositely-disposed partition edges.
 14. The apparatus as defined in claim 13, wherein said rail portions urge the said partition edges Which they engage upwardly against said flange portions hooding said tubular chamber.
 15. A drop-away fire vent, comprising in combination: frame means defining a generally tubular upright chamber and including fixed, generally rigid wall portions and flange portions above said wall portions which partially hood said tubular chamber; a closure means having an outer periphery generally corresponding to, but at least somewhat smaller than, the cross section of said chamber, said closure means disposed within said chamber beneath said flange portions; and collapsible support means between said rigid wall portions and said closure means, for normally supporting the latter in position beneath said flange portions but for collapsing in response to heat to allow said closure means to drop downwardly by gravity within said chamber to vent the latter; said closure means including a closure partition whose edges define said outer periphery and a mounting frame for said partition, said mounting frame having at least two oppositely-disposed rail portions underlying and supportively engaging a pair of oppositely-disposed partition edges, said rail portions including a condensation-collecting apron means disposed beneath and extending both laterally inwardly and outwardly of certain of said partition edges.
 16. The apparatus as defined in claim 15, wherein said apron means has yieldably deformable portions.
 17. The apparatus as defined in claim 15, wherein said apron means includes yieldable portions extending outwardly from said partition edges and over at least parts of said frame means chamber, said yieldable portions being sufficiently yieldable to deform and pass over said parts of said frame means and allow said apron means and said rail portions to move axially within said tubular chamber over and past said parts of said frame means. 